1. Field of the Invention
The present invention relates to a sheet feeding apparatus and an image forming apparatus and particularly to a construction to prevent over-stacking of sheets on a sheet supporting portion.
2. Description of the Related Art
Heretofore, in an image forming apparatus such as a printer and a copying machine, a sheet feeding apparatus is provided for feeding out a sheet to an image forming portion from a sheet supporting portion on which a plurality of sheets are stacked.
In the sheet feeding apparatus constructed as above, when more than a predetermined quantity of sheets are stacked on a sheet feed tray (hereinafter referred to as over-stacking of sheets), defective sheet feeding occurs.
Methods to prevent such over-stacking of sheets include a method of putting a mark indicating an upper limit of the sheet stacking height on a width regulating member arranged on the sheet feed tray, for example. FIG. 8A is a view showing a construction of a conventional sheet feeding apparatus, which employs this method. At a width regulating member 109 arranged on a sheet feed tray 101, a mark 109a indicating the upper limit of the sheet stacking height is provided. When a user sets a sheet bundle on the sheet feed tray, the user is supposed to visually check this mark 109a so as to prevent over-stacking of the sheets.
However, when the mark 109a indicating the upper limit of stacking is provided on the width regulating member 109 in this way, the user may not notice the mark 109a and causes an over-stacking state. In this case, feeding-out of sheets by a pickup roller (not shown) cannot be carried out reliably, and defective sheet feeding might occur.
In order to prevent such over-stacking without relying on visual check by the user of the upper-limit mark of sheet stacking, there is a method of providing a member for restricting a stacking height on the width regulating member. FIG. 8B shows a construction of a conventional sheet feeding apparatus, which employs this method, and a restricting member 109b for restricting the sheet stacking height is provided on the width regulating member 109.
When the user sets the sheet bundle on the sheet feed tray, the user is supposed to prevent over-stacking of the sheet by setting the sheet in a range not exceeding this restricting member 109b for the sheet stacking height.
However, in the conventional sheet feeding apparatus provided with the restricting member 109b for the sheet stacking height on the width regulating member in this way, when the sheet bundle is to be set on the sheet feed tray, the sheet bundle might be forced to be below the restricting member 109b and set thereon. In this case, the sheets which were forced in and set are held between the restricting member 109b and the sheet feed tray. Therefore, even if the sheet is to be fed by the pickup roller, sheet feed resistance is generated to prevent feeding-out and cause defective sheet feed.